To assess the frequency and spatial pattern of FOXC2 expression in the most common subtype of ovarian cancer, high-grade serous ovarian carcinoma (HGSOC), immunohistochemical analysis was performed on 50 HGSOC samples of which 20 were whole sections and 30 were arranged into a tissue microarray (TMA) (1.5 mm cores; no overlap with the whole-section samples). The gene discussed is FOXC2; the disease is ovarian serous carcinoma.